1. Field of the Invention
Exemplary embodiments of the present invention relate to a method of driving a light source, a light source device for performing the method, and a display device having the light source device. More particularly, exemplary embodiments of the present invention relate to a method of driving a light source for local dimming driving, a light source device performing the method and a display device having the light source device.
2. Description of the Related Art
Generally, liquid crystal display (“LCD”) devices have thinner thicknesses, lighter weight and lower power consumption than other types of display devices, and thus LCD devices are widely used, not only for monitors, laptop computers, and cellular phones, but also as widescreen televisions. A typical LCD device includes an LCD panel displaying images using light transmissivity of liquid crystal and a backlight assembly providing the LCD panel with light.
The typical backlight assembly includes a light source that generates light. For example, the light source may be a cold cathode fluorescent lamp (“CCFL”), a hot cathode fluorescent lamp (“HCFL”) or a light-emitting diode (“LED”). The use of LEDs is advantageous as a light source for the LCD panel because the LED has low power consumption and high color reproducibility.
Recently, a local dimming method dividing the LCD panel into a plurality of regions and controlling amounts of the light emitted from the backlight based on a gray level of the image displayed in each of the regions has been developed in order to improve the contrast ratio of the image displayed on the LCD device. The local dimming method reduces amounts of light from LEDs by reducing the amount of a driving current provided to the LEDs that are located in a region displaying a darker image than other regions. Additionally, the local dimming method increases the amounts of the light from the LEDs by increasing the amount of the driving current provided to the LEDs that are located in a region displaying a brighter image than other regions.
As described above, the typical backlight assembly includes a plurality of LED strings and a multichannel current controller for providing the driving current to the LED strings connected to each other in parallel when LEDs that are connected to each of the LED strings in series are driven using the local dimming method.
The typical multichannel current controlling circuit generally controls resistance variations among the LED strings so that the driving currents flowing through the LED strings are controlled to be substantially the same as each other. When an LED is shorted in the LED strings, the multichannel current controlling circuit consumes an amount of power corresponding to the shorted LED by producing heat in order to maintain the previously supplied driving current to the remaining LEDs. The shorted LED may damage the multichannel current controlling circuit due to the excess heat generated thereby.